The present invention relates to a resin composition which comprises a polyphenylene ether resin and a copolyamide resin.
More particularly, it relates to a novel thermoplastic resin composition which comprises a resin composition comprising a polyphenylene ether, an aliphatic polyamide and a specific compatibilizing agent, to which a thermoplastic aromatic copolyamide and/or an aromatic nuclear-hydrogenated copolyamide is added at a specific ratio.
The thermoplastic resin composition is excellent in mechanical properties, especially less in reduction of flexural modulus when absorbing water and superior in processability.
The thermoplastic resin composition can be made into shaped articles, sheets, etc. by injection molding, extrusion molding, etc.
Resin compositions comprising a polyphenylene ether resin and a polyamide resin such as nylon 6 or 66 have been known, as disclosed in Japanese Patent Publication (Kokoku) Nos. 45-997 and 53-47390, Japanese Patent Publication (Kokai) Nos. 56-16525, 56-26918, 61-66452, 62-151456, 62-129350 and 62-250050 and U.S Pat. No. 4,315,086.
These resin compositions have improved respective defects of the two resin components, for example, low processability and low solvent resistance of the polyphenylene ether resin and low heat resistance and high water absorbency of the polyamide resin. Thus, they are recently extended to a wide range of applications such as electric parts, mechanical parts, sports goods, automobile parts, especially exterior trim parts.
However, even such resin compositions still have problems in properties for practical use.
Resin compositions comprising a polyphenylene ether and an aliphatic polyamide having a relatively high concentration of amide group such as nylon 6, nylon 66 and nylon 46 are fairly improved in water absorbency, compared with polyamide per se. However, they still have a significant defect that water absorption varied depending on content of polyamide, and absorption of water of such a small amount as about 1% based on the composition causes considerable deterioration of properties, especially reduction of flexural modulus.
Furthermore, thermal expansion coefficient of these resin compositions are lower than that of polyamide per se, but still higher than that of metallic materials and that of polyphenylene ether per se. Thus, they have another defect that their distortion is great at high temperature due to such thermal expansion.